Quickly delete data from all tables in a database

Quick deletion of data from all tables in a database

Select ' TRUNCATE TABLE ' + name + '; ' from sysobjects where xtype= ' U ' ORDER by Name ASC;

After the execution of this statement, all the tables in the database are queried, and the TRUNCATE statement is executed after copying it.

sysobjects

Each object created within the database (constraints, default values, logs, rules, stored procedures, and so on) occupies a single row in the table. Only within tempdb , each temporary object occupies one row in the table.

Column Name	Data Type	Description
Name	sysname	The name of the object.
Id	Int	The object identification number.
Xtype	CHAR (2)	The object type. Can be one of the following object types: C = CHECK Constraint D = defaults or DEFAULT constraints F = FOREIGN KEY constraint L = Log FN = Scalar function IF = Inline Table function P = Stored Procedure PK = PRIMARY KEY constraint (type is K) RF = copy Filter stored procedure S = System table TF = Table function TR = Trigger U = User Table UQ = UNIQUE constraint (type is K) V = view X = Extended Stored Procedure
Uid	smallint	The user ID of the owner object.
Info	smallint	Keep. Internal use only.
Status	Int	Keep. Internal use only.
Base_schema_ Ver	Int	Keep. Internal use only.
Replinfo	Int	Keep. For replication use.
Parent_obj	Int	The object identification number of the parent object (for example, for a trigger or constraint, which is the table ID).
Crdate	Datetime	The date the object was created.
Ftcatid	smallint	Full-text catalog identifier for all user tables registered for full-text indexing, or 0 for all user tables that are not registered.
Schema_ver	Int	The version number, which is incremented each time the schema of the table changes.
Stats_schema_ Ver	Int	Keep. Internal use only.
Type	CHAR (2)	The object type. Can be one of the following values: C = CHECK Constraint D = defaults or DEFAULT constraints F = FOREIGN KEY constraint FN = Scalar function IF = Inline Table function K = PRIMARY KEY or UNIQUE constraint L = Log P = Stored Procedure R = Rule RF = copy Filter stored procedure S = System table TF = Table function TR = Trigger U = User Table V = view X = Extended Stored Procedure
Userstat	smallint	Keep.
Sysstat	smallint	Internal state information.
Indexdel	smallint	Keep.
Refdate	Datetime	reserved for later use.
Version	Int	reserved for later use.
Deltrig	Int	Keep.
Instrig	Int	Keep.
Updtrig	Int	Keep.
Seltrig	Int	Keep.
Category	Int	Used for publishing, constraints, and identification.
Cache	smallint	Keep.

Truncate and delete without a WHERE clause, and drop deletes the data in the table

Different points:
1. Truncate and delete only delete data without deleting the structure of the table (definition)
The drop statement will delete the structure of the table that is dependent on the constraint (constrain), trigger (trigger), index (indexed); Stored procedures/functions that depend on the table are preserved, but become invalid states.
The 2.delete statement is DML, which is placed in the rollback segement, which takes effect after the transaction is committed, and is triggered when the corresponding trigger is executed.
Truncate,drop is DDL, the operation takes effect immediately, the original data is not placed in the rollback segment and cannot be rolled back. Operation does not trigger trigger.
The 3.delete statement does not affect the extent occupied by the table, and the high waterline (watermark) remains in its original position.
Apparently the drop statement frees all the space occupied by the table.
Truncate statement by default see space released to minextents extent unless reuse storage is used; Truncate will reset the high watermark (back to the beginning).
4. Speed, in general: drop>; Truncate >; Delete
5. Security: Use Drop and truncate carefully, especially when there is no backup. Otherwise, it's too late to cry.
For use, to delete some data rows with delete, note the WHERE clause. The rollback segment should be large enough.
Want to delete the table, of course with drop
You want to keep the table and delete all the data. If it is unrelated to the transaction, use truncate. If it is related to a transaction, or if you want to trigger trigger, use Delete.
If you are defragmenting the inside of the table, you can use truncate to keep up with reuse stroage and re-import/Insert Data

Quickly delete data from all tables in a database